The present invention relates to a flexible connection for supplying cooling air to a movable grate cooler. The cooler comprises alternate rows of movable stationary grate elements designed for cooling granular material that has been subjected to heat treatment in a kiln, for example a rotary kiln.
When used in connection with a rotary kiln, the grate cooler is mounted at the outlet end of the kiln and is adapted to receive the hot material discharged from the kiln. The material is distributed across the grate surface of the grate cooler and is conveyed in a bed across the grate surface. The material is thereby conveyed through the cooler by the reciprocating movement of the movable grate elements, while the material bed is simultaneously swept by cooling air from the perforated surface of the grate elements.
Grate elements such as described herein are known, for example, from Danish patent application No. 1227/92. Since, generally, the material bed on the grate surface is not homogeneously sized, the cooling air is often separately fed to each single grate element and can thus be controlled for optimum cooling. Consequently, this requires an air supply connection for each of the single grate elements, both the stationary and the movable elements.
Although it is not particularly difficult to supply air to the stationary grate elements, it is an essential requirement that the air connection for the movable grate elements has the required degree of flexibility so that the connection can follow the reciprocating movement of these grate elements.
Therefore, the flexible connection often consists of a flexible hose, such as rubber or canvas or even stainless steel formed as an elastic bellows.
However, such flexible connections are exposed to wear and degradation due to the continuous bending strains. This is further aggravated by exposure to the influence of very hot material which falls down between the grate elements.